Yieldable wall assembly for the transportation of low-temperature fluids



Dec. 30. 1969 w. SAMAGA 3,486,286

YIELDABLE WALL ASSEMBLY FOR THE TRANSPORTATION OF LOW-TEMPERATURE FLUIDS Filed April 12, 1968 3 Sheets-Sheet 1 INVENTOR.

WILHELM SAMAGA F l G 8 BY WxQ jbsi ATTORNEY Dec. 30. 1959 w. sAMAGA3,486,286

YIELDABLE WALL ASSEMBLY'FOR THE TRANSPORTATION OF LOW-TEMPERATURE FLUIDSFiled April 12, 1968 I 3 Sheets-Sheet 2 INVENTOR.

WILHELM SAMAGA BY R99 ATTORNEY W. SAME GA YIELDABLE WALL ASSEMBLY FORTHE TRANSPORTATION Dec. 30, 1969 v 0F LOW-TEMPERATURE FLUIDS Filed April12, 1968 3 Sheets-Sheet 5 FIG.5

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ATTORNEY United States Patent 3,486,286 YIELDABLE WALL ASSEMBLY FOR THETRANSPORTATION OF LOW-TEMPERA- TURE FLUIDS Wilhelm Samaga, Trostberg,Germany, assignor to Linde Aktiengesellschaft, Wiesbaden, Germany, acorporation of Germany Filed Apr. 12, 1968, Ser. No. 721,043 Claimspriority, application Germany, Apr. 25, 1967, L 56,338 Int. Cl. E04111/76; E0411 7/04 US. Cl. 52-410 10 Claims ABSTRACT OF THE DISCLOSURE Areceptacle assembly for the retention of low-temperature fluidscomprising a plurality of plates having parallel end edges and a pair ofinwardly directed lateral edges, the edges being formed with upwardlyand outwardly turned flanges welded together at their corners to formpans and to adjoining plates of corresponding configuration so that thejunctions of the end edges of each row of plates is offset from thejunctions of the end edges of an adjoining row, the plate is secured toa rigid wall, with interposition of a thermally insulating layer, viathermally nonconductive bolt assemblies anchored at the midpoint of thedouble trapezoids formed by each plate.

My present invention relates to containers for the transportation oflow-temperature fluids and, more particularly, to a tank or compartmentin a seagoing vessel for the transportation of liquefied gases at lowtemperature.

In the commonly assigned copending application Ser. No. 664,066, filedAug. 29, 1967 by myself, Hans Pro'gler, Hermann Ehms and RudolfEickemeyer, entitled Tankship for Liquefied Gases, there is disclosed atankship for the transportation of liquefied gases (e.g. liquidhydrocarbons such as methane, ethane or propane, or airrectificationproducts such as nitrogen, or ammonia) whose hull forms a holdcontaining a plurality of tanks thermally insulated from the hull andseparated therefrom by a continuous sheet-metal skin. The skin, whichmay flex in response to temperature fluctuations, is composed of plateswelded together in fluid-tight relationship along their peripheries atupstanding flanges so that the welded peripheries form expansion jointsor folds accommodating expansion and contraction of the skin. Betweenthe sheet-metal skin and the hull of the ship, there is provided a layerof insulation preferably of load-supporting or relatively incompressiblecharacter. In addition, the system of that application provides parallelarrays of shear-rail assemblies supporting the tank in loadtransmittingrelationship with the hull while thermally insulating the tanktherefrom. The earlier application, Ser. No. 663,577, filed Aug. 28,1967 by Rudolf Becker and also commonly assigned, describes animprovement in which insulating bolts attach the sheet metal outer wallof a double-wall assembly to the hull of the ship with an interveninglayer of load-supporting insulation. As pointed out there, a furtherlayer of insulation, preferably of the nonsupporting type, may beinterposed between the inner wall of the vessel and this intermediatesheet-metal layer. The bolt assembly described in that applicationcomprises a bolt head welded sealingly to the sheet-metal layer andwhose shank is threaded into a cylindrical post of thermally insulatingmaterial, the post being threadedly anchored in a sleeve upstanding fromand welded to the hull of the vessel.

In the sheet-metal skin of the aforementioned copending applications,elasticity is gained by providing a 3,486,286 Patented Dec. 30, 1969 iceplurality of plates in contiguous relationship, the plates havingupturned flanges at their peripheries welded at the corners to formindividual pans. The flanges, which diverge upwardly, are weldedtogether at outer lips to form a continuous partition or wall precludingpassage of fluid therepast. The flanges or upwardly bent edge portions,when welded together, form folds in the continuous wall which permitexpansion and contraction of the sheets in response to the hightemperature fluctuations which are sustained by the walls upon fillingof the tanks or discharging of the cargo. When the plates are generallyretangular, they are characterized by a rigidity enhanced, in part, bythe fact that the folds are lined up and are incapable of yieldingsatisfactorily in the longitudinal direction of these folds. As aconsequence, the plates must sustain considerable stress which givesrise to a tendency to tearing at the locations at which the plates areaflixed to the hull structure or the outer rigid vessel wall.

It has been found that the individual mounting of the fixed point of anintermediate or inner sealed sheet-metal skin for tankships andreceptacle structures accommodated within the hull of a seagoing vessel,as proposed heretofore, is relatively complex and expensive whenaccomplished in the manner described above.

It is, therefore, the principal object of the present invention toprovide an improved yieldable wall structure for a vessel of thecharacter described in which the stress applied to the plates isdecreased and the mounting assembly prevents tearing of the sheets.

It is another object of the present invention to provide an improvedmounting assembly for hermetically sealed sheet-metal walls spaced fromthe hull of a ship by a layer of load-supporting thermal insulation.

According to an important feature of this invention, the stressdeveloped in the individual plates, which are peripherally weldedtogether in contiguous relationship to form a continuous fluid-tightpartition adapted to withstand low-temperature fluids, is relieved byoffsetting the junctions between the plates, from plate to plate alongthe continuous skin. This is accomplished by imparting to the plates ageometric configuration which corresponds, substantially, to adouble-trapezoid joined at the corresponding small base thereof. Morespecifically, the plates are provided with a pair of parallel end edgesand a pair of inwardly directed lateral edges and are joined together inoverlapping relationship so that the junction between a pair of ends ofend-aligned plates is disposed substantially intermediate the ends ofthe neighboring side-aligned plates. Thus the plates of the presentinvention are connected end to end in adjacent rows which are offsetsubstantially by about half the length of the plates and each plate iswidest at its ends and narrowest at an intermediate region correspondingto the location of closest approach of the inwardly turned lateralsides. Preferably, this intermediate location lies at the center of theplate. As in the prior systems, each of the edges is formed with anupwardly and outwardly turned flange, the flanges along the periphery ofeach plate being welded together at their corners, A single boltassembly (e.g. as described and claimed in my concurrently filedcopending application Ser. No. 721,042 entitled Tank Assembly for theTransportation of Low-Temperature Fluids) secures the plate to the rigidwall at the center of the plate.

According to a more specific feature of this invention, the lateraledges of each plate include acute angles of 60-80 with the parallel endsand thereby intersect at an obtuse angle of substantailly -160 at themidsection of the plate so that an axial plane through thefastening-bolt assembly intersects the lateral edge of the plate atthese junctions. This plane thus can be considered to divide each plateinto a pair of mirror-symmetrical trapezoids formed integrally with oneanother at the short base corresponding to the line at which the planeintersects the plate.

According to still another feature of this invention, each of theupwardly and outwardly turned edge flanges is bent outwardly with aradius to form a lip whose flank lies perpendicularly to the body of theplate and is welded in abutting relationship to the confronting lip ofthe tapering plate.

It will be understood that the parallel end edges of the plates may beso widely spaced that the lateral edges are turned alternatively,inwardly and outwardly so as to encompass several pairs of back-to-backtrapezoids and that the parallel edges themselves of a number of pansmay be integral and the folds formed by bending the plates rather thanwelding plate sections together. This arrangement is particularlydesirable when plates of up to meters in length are used.

Another feature of the invention resides in the use of a snap-typejunction between a supporting post and the sheet metal intermediate wallor skin by providing each of the sheet metal plates of the skin with athroughgoing aperture at its single fixed point and surmounting thisaperture with a cap whose interior registers with the aperture and isperipherally welded to the sheet metal at a seam spacedly surroundingthe aperture. The mounting assembly comprises an upstanding post ofthermally insulating material, which may be threadedly received in asleeve welded to the hull of the ship, the post being formed with anupstanding pin adapted to pass through the aperture of the sheet metalskin and to be received in the cap disposed thereabove. A spring ring isanchored in the cap and is designed to snap into a circumferentialgroove formed in the pin beyond a conical spreading head of the boltwhose small-diameter tip is receivable within the ring to expand thelatter. Thus the inner diameter of the ring, in its relaxed condition,is less than the outer diameter of the spreading cone or tip at theupper end of the shank of the pin or both. The interior of the cap maybe formed with an inwardly open circumferential groove receiving thering and adapted to lock the ring and the pin against movement in thespread condition of the ring.

According to a more specific feature of the invention, the cap isprovided with an outwardly extending peripheral flange whose axial facelies flush with the corresponding surface of the sheet metal skin and isperipherally welded thereto. The pin, according to the presentinvention, is anchored in an insulating post but need not be threadedinto the latter. Thus, I provide a stepped bore in the insulating postwith a smaller diameter portion registering with the aperture in thesheet metal skin and a larger diameter portion disposed between thesmaller diameter portion and the tankship hull or outer wall of adouble-wall tank. The junction between the larger and smaller diameterportions of the bore forms a shoulder against which the pin is seated atits end remote from the frustoconical camming portion.

The remote end of the pin may be provided with a head or, in accordancewith still another specific feature of this invention, a frustoconicaltip symmetrical with that head at the upper end of the pin and acorresponding groove in which a spring ring is anchored to retain awasher against the shoulder of the post.

The above and other objects, features and advantages of the presentinvention will be more readily apparent from the following description,reference being made to the adcompanying drawing in which:

FIG. 1 is a plan view of a portion of an intermediate sheet metal skinfor tankships and the like embodying the present invention;

FIG. 2 is a detailed view, drawn to an enlarged scale of part of thisskin;

FIG. 3 is a cross-sectional view taken along the line IIIIH of FIG. 2;

FIG. 4 is a cross-sectional view taken along the line IVIV of FIG. 2;

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 1;

FIG. 6 is a view corresponding to FIG. 5 showing another embodiment ofthis invention;

FIG. 7 is a diagram of the snap-lock arrangement of this invention; and

FIG. 8 is a plan view illustrating another feature of the invention indiagrammatic form.

In FIGS. 1 and 2, I show a sheet metal intermediate skin adapted toyield with temperature variation (FIG. 2) and comprising a plurality ofsheet metal plates 1 of double-trapezoidal configuration. The plates areformed with mutually parallel end edges 24, forming the longer bases ofthe two trapezoids constituting each plate, and with inwardly extendinglateral edge portions 22 and 23 including acute angles with therespective bases and intersecting substantially at the welded seams 25'.The seams 25' constitute junctions between the edges 22 and 23 alongeach side of the plates 1. At the junctions between the portions 22 and23 and the ends 24 of each plates, further welded seams 25 are provided.Each of the plates 1 thus forms an upwardly open pan as describedearlier.

As will be apparent from FIG. 5, each of the lateral walls 22, 23 andthe end walls 24 is constituted of upwardly and outwardly turned flanges1d, 1e shown for the respective plates 1a, 1b and 10 illustrated to liein contiguous relationship in FIG. 5. The flanges 1d and 1e are turnedoutwardly at angles of approximately 10 to 20 from the vertical (angle 5in FIG. 3) and have bent-over lips 26 whose outer flanks 26 lie in thevertical plane P of each junction and are butt welded to the confrontingflanks of the adjoining flanges.

Referring again to FIGS. 1 and 2, it can be seen that the adjoiningplates have their end junctions A, B, C offset from the junctions A, B,C' by approximately half the length of the plates 1 and that each of theplates 1 is retained upon the rigid wall by a single bolt assemblyrepresented generally at 27 and located at the center of the respectiveplate. The bolt asesmbly is deisgned to prevent transfer of heat to andfrom the plates 1.

In FIGS. 2-4, the shrinkage and expansion of the plates is represented.In these figures, the position of the plates upon welding and aftermounting the assembly is represented by solid lines while the positionof the plates upon introduction of low-temperature fluid (e.g. liquefiedgases) into the tankship hold is represented by dot-dash line. When theplates 1 are chilled, the shrinkage results in a contraction of thelongitudinal edges 24 and a deflection of the lateral edges 22 and 23into the dot-dash line position illustrated in FIG. 2, the edges 22 and23 assuming an angle a. The angle or should range from 60 to Theforeshortening of the plates causes the deflection of folds illustratedby dot-dash line 1n FIGS. 3 and 4. In FIG. 8, I show a system in whichthe end edges 34 are spaced up to 20 meters apart and may be welded toother plates or constitute the sides of the compartment as desired. Inthis case, the inwardly turned lateral edges 32 and 33 do not intersectdirectly but are spaced by intervening stretches 33' and 32' so as toprovide a pair of double trapezoids separated by the dot-dash line 34'.A further fold, parallel to the folds 34 may be provided along thisline, preferably unitarily with the plate 31. Referring again to FIG. 1,it can be seen that the intersecting seams 25 of the lateral edges 22,23 coincide with the vertical plane P through the bolt assembly 27 (seeFIG. 5).

As can be seen from FIGS. 5-7, between the sheet metal skin formed byplates 1 and the steel hull 8 of the ship, I provide a layer 8a ofload-supporting thermal insulation, as described in application Ser. No.664,066, to form a thermal barrier preventing heat loss from the tankcompartment defined by the sheet metal skin to the wall 8 of the vessel.

A typical insulating material is Ferrozel (i.e. shearresistant andcompression-resistant fiberglass-reinforced phenolic resinsee FrenchPatent 1,490,834).

To secure the sheet metal plates 1 in place, I provide each with theassembly 27 which includes an upstanding internally threaded sleeve 9having a height equal only to a small fraction of the spacing of theplates 1 from the hull 8 and welded to the latter along a seam 9a. Apost 10 of load-supporting material of poor thermal conductivity (e.g.Ferrozel or a ceramic thermal insulator) has a threaded portion 10ascrewed into the sleeve 9 so that the outer periphery of the post It) isflush with the outer periphery of this sleeve. The post 10 is formedwith a stepped bore whose large-diameter portion 10b joins thesmall-diameter portion 100 at a shoulder 10d serving to anchor the head11a of a pin 11 extending upwardly through the small-diameter portion100 and having a frustoconical end 1117.

The sheet metal skin 1 is formed at each of its fixed points with anaperture 1 registering with the bore 10b, 10c and with the internalcavity 4 of a cap 3.

At its lower end, the cap 3 is formed with an outwardly extending flange3a lying flat against the sheet metal skin 1 and peripherally weldedthereto at 6. Within the interior 4 of the cap 3, I have provided aninwardly open peripheral groove 5 which receives a spring ring 14adapted to be wedged outwardly by the frustoconical upper end 11b of thebolt 11 as the cap 3 is thrust over this bolt. Behind the frustoconicaltip 11]), the bolt or pin 11 is formed with an outwardlly opencircumferential groove 13 adapted to receive part of the ring 14 whenthe latter springs back after it has been wedged outwardly. To supportthe bolt 11, I provide a backing block 12 of thermally insulatingmaterial which fills the large diameter portion 16b of the bore of post10 and is seated against the hull 8.

As can be seen from FIG. 7, the frustoconical end 11!) of the pin 11 hasan outer diameter d which is less than the inner diameter D of the ring14 in its relaxed position. After the caps 3 have been welded to theplates 1, the plates may be placed with their apertures 1g over the pins11 and set by relatively light taps upon the caps 3. The taps drive thecaps 3 over the frustoconical tips 11b of the bolt 11 until the rings14, which initially are spread in the direction of arrows 1417, springback into the grooves 13, thereby retaining the plates upon the pins. Anextremely rapid rate of assembly is thus permitted.

In the embodiment of FIG. 6, a cap is provided to retain the sheet-metalskin 1' upon the bolt 11' in the manner illustrated in FIGS. 5 and 7. Inthis embodiment, however, the lower end of the bolt 11 is formed with afrustoconical tip 115' behind which a circumferential groove 15 isformed. A split ring 16 is snapped into this groove and bears against abacking washer 17 to anchor the bolt 11 against the shoulder 10d of thepost 10 which otherwise has the configuration previously described. Thecylindrical block 12 here supports the frustoconical end 11b of thebolt.

I claim:

1. In a receptacle for the storage or transportation of low-temperaturefluids wherein a fluid-tight elastic sheetmetal wall is spaced from arigid wall by a layer of thermal insulation, the improvement whereinsaid elastic wall comprises a plurality of adjoining rows of generallysimilar plates, each of said plates having a pair of parallel end edgesconstituting relatively wide portions of the plate and inwardly turnedlateral edges forming at a region of closest approach a relativelynarrow portion of the plate, said edges each being provided withupwardly and outwardly turned flanges welded together at the corners ofeach plates to form a respective pan therefrom, the flanges of thelateral edges of said plates of each row being welded to the contiguousflanges of the lateral edges of the plates of an adjoining row beingoflset relatively to dispose the ends of the plates of one rowsubstantially at said regions of the plates of an adjoining row.

2. The improvement defined in claim 1, further comprising a boltassembly of relatively low thermal conductivity securing each of saidplates to said rigid wall at substantially the geometrical center of theplate.

3. The improvement defined in claim 2 wherein said flanges haveoutwardly turned lips welded to the juxtaposed lips of the flanges ofthe adjoining plates.

4. The improvement defined in claim 2 wherein the end edges of theplates on each row are welded together contiguously.

5. The improvement defined in claim 2 wherein each of said plates hasthe configuration of a double trapezoid With coincidental small bases.

6. The improvement defined in claim 5 wherein each of said boltassemblies comprises a load-supporting post secured to said rigid walland extending toward said elastic wall, a pin anchored in said post andextending therebeyond away from said rigid wall, each of said platesbeing provided at its geometrical center with an aperture receiving thecorresponding pin and a cap sealingly anchored to the plate and havingan interior registering with said aperture for receiving an end of thecorresponding pin, each cap and pin being formed with spring-ring meansfor locking the cap onto the pin upon insertion of the pin into the cap.

7. The improvement defined in claim 6 wherein said cap is formed with aninwardly open peripheral groove, said spring-ring means including aresilient ring receiving said groove, said end of said pin having afrustoconical configuration and being receivable in the respective ringto expand same, each pin being provided with an outwardly opencircumferential groove behind the frustoconical configuration of saidend to receive said ring upon its expansion by said end of said pin.

8. The improvement defined in claim 7 wherein said post is formed with astepped bore having a large diameter portion and a small diameterportion defining between them a shoulder anchoring said pin againstmovement in the direction of said elastic wall, said pin having anotherend spaced from said rigid wall, said assembly further comprising athermally insulating block received in said large diameter portion ofsaid bore and seated against the other end of said pin and said rigidwall.

9. The improvement defined in claim 8 wherein each of said caps isformed with an outwardly extending annular flange lying flat against therespective sheet-metal plate and being peripherally welded thereto.

10. The improvement defined in claim 8 wherein said assembly furthercomprises a sleeve welded to said other wall and threadedly receivingsaid post.

References Cited UNITED STATES PATENTS 3,367,699 2/1968 Witt 52- 110 X3,302,358 2/1967 Jackson 52573 2,876,927 3/1959 Henning 52573 X2,736,400 2/1956 Gay et al 52573 X FRANK L. ABBOTT, Primary Examiner S.D. BURKE III, Assistant Examiner US. Cl. X.R.

